The valley in the Southern Peruvian Andes where fine root growth and organic layer thickness were measured over several yearsThe Earth's atmospheric carbon dioxide has remained remarkably stable over the past 24 million years. And scientists believe they have now solved part of the mystery as to why this has been the case, despite changing geological conditions. They believe that ancient tree roots in the mountains may play an important role in controlling long-term global temperatures acting as a type of natural 'thermostat'.

When CO2 levels became too low for plants to grow properly, forests in mountains appear to have kept the climate in check by slowing down the removal of carbon dioxide from the atmosphere. 'This study shows how trees can act as brakes on extreme climate change, and the roots of trees in tropical mountains such as the Andes play a disproportionate role,' Yadvinder Malhi, professor of Ecosystem Science at Oxford University told MailOnline. 'However, these responses take thousands to millions of years and cannot do much to slow the rate of global warming we are experiencing this century.'

In a warmer world, tree roots are more likely to grow into the mineral layer of the soil, breaking down rock which will eventually combine with carbon dioxideResearchers from Oxford and Sheffield Universities discovered that temperatures affect the thickness of the leaf litter and organic soil layers, as well as the rate at which the tree roots grow.